1. Field of the Invention
The present invention relates to an illuminating device, in particular to a LED lamp and a heat sink having a wound heat pipe.
2. Description of Prior Art
Illuminating devices are very important tools in the civilization of human beings, by means of which people can recognize their locations even in a dark environment. Tungsten lamps are one kind of illuminating devices, in which a tungsten filament is used as a light-emitting source. Thus, the tungsten lamp has a simple structure. When an electric current passes through the tungsten filament, it can be heated to emit light, so that the tungsten lamp can be used for illumination. However, the tungsten filament is prone to be blown and thus the lifetime of the tungsten lamp is short.
With the advancement of science and technology, LED lamps are developed. Light emitting diode (LED) is a solid light source capable of converting electricity into light energy. The LED has advantages of small volume, low driving voltage, fast response and long lifetime, so that LED lamps have been widely used to replace the traditional tungsten lamps.
The conventional LED lamp includes a lamp base, a lamp shroud mounted in the lamp base, and a LED module received in the lamp shroud to abut against the inner bottom wall of the lamp shroud. The LED module is electrically connected to the lamp base. The lamp shroud is made of metallic materials. The heat generated by the LED module is conducted to the lamp shroud for heat dissipation. However, such a heat-dissipating effect is insufficient.
In order to increase the illuminating range and brightness of the LED lamp, the LED module usually has a plurality of LEDs. With the increase of the number of LEDs and the development of high-power LEDs, the amount of heat generated by the LED module is raised to a large extent. If the heat is not dissipated immediately, the heat will be accumulated in the LED module to deteriorate the lifetime of the LED lamp and thus increase the maintenance cost.
Thus, in order to dissipate the heat more efficiently, the outer surface of the metallic lamp shroud is usually provided with a plurality of heat-dissipating fins to improve the heat-dissipating effect of the LED lamp. However, the heat generated by the LEDs is conducted to the lower portion of the lamp shroud, the lower portion of the heat-dissipating fins, the upper portion of the lamp shroud, and finally to the upper portion of the heat-dissipating fins. Thus, the heat-conducting path is long and the heat-conducting speed is low. Furthermore, the heat is not uniformly conducted, so that the heat may be accumulated easily in the lower portion of the lamp shroud. In other words, due to the above-mentioned structure, the heat-dissipating effect of the heat-dissipating fins is not utilized sufficiently.
In view of the above, the present Inventor proposes a novel and reasonable structure based on his researches and expert knowledge in order to solve the problems in prior art.